I have got a problem in the 3rd revision of scematic/layot which I do not understand.
When I take the new unprogrammed PCB's and power up (POR) - then I can't program it.
So I looked at the RESET-Pin - and this got a voltage of 390mV.
The RESET Pin is normally Pulled up with a 470R Resistor.
If I connect the RESET Pin direct to 3.3V - a current of approx 30mA is measurable - so it looks llike the Reset drives as an Output.
I tried with different PCBs - same behaviour.
So does anybody has a idea what could be?
Some measurements later...
The RESET Pin of the uC is driven low by the Kinetis itself for some microseconds - then released - then driven low again - and so on...
It looks like a Pulse Width Modulation with a frequenc of approx 3 kHz.
What could be a reason for this behavior?
Best Regards Manfred